Thermal relay



A'roRNE-Y R 5. i O 1 WA# y m f w trllllnrlrblllnllllllll l, {HHHM 7 www w veel., n llll l K 2 v 9 w me M l n E p z R J w m d T u SSV i F Oct. 28, 1924 WITNESSES:

Patented Oct. 28, 192.4,

UNITED STATES PATENT OFFICE.

THOMAS S. PERKINS, 0F PITTSBURGH, FENNSYLVANIA, ASSIGNOR TO' WESTING- HOUSE ELECTRC & MANUFACTURING COMIANY, A CORGRATION OF PENNSYL- VANIA.

THERMAL RELAY.

Application filed fully 15,

To all whom t may concern: l

Be it known that I, THOMAS S. PERKINS, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Thermal Relays, of which the following is a specification.

My invention relates to electrical protective devices and particularly to thermal relays.

One object of my invention is to provide a thermal relay in which the temperature of the controlling elements shall bear a definite relation to the temperature of the apparatus.

Another object of my invention is to provide a thermal relay that shall have suf ficient time interval in its operation to effectively protect electrical apparatus from overheating.

Another object of my invention is to provide a device, of the above-indicated character, that shall be simple and economical in construction and effective in its operation.

In practicing my invention, l provide a magnetizing means, a movable member responsive thereto Vand means having a lowmelting point, such as wax, for precluding any movement of the movable means in .response to the magnetizing means until a predetermined temperature is developed in the wax. The movable member, when actuated, effects the disengagement of two contact members and thereby controls the opening of an auxiliary circuit.

Figure 1 is a front view, partially in elevation and partially in section, of a device embodying my invention;

Fig. 2 is a diagrammatic view of an electrical circuit illustrating the connections thereto of the deviceillustrated in Fig. 1; Fig. 3 is a schematic viewv illustrating the .disposition of the movable member of the device shown in Figi, and

F ig. 4 is a sectionalview taken on the line IV-IV Vof Fig. 3.

A translating device 1 is adapted to receive energy from al circuit 2 through a circuit interrupter 3 and is provided with a thermal device 4 for protection against overheating. The interrupter 3 is provided with a holding magnet 5 and a restraining spring 6 that is adapted to open the interrupter 3 rentvalue.

1920. Serial No. 396,526.

when'the circuit of the holding magnet 5 is opened by the thermal device 4.

The thermal device 4 comprises a cylindrical member 7 of insulating material and two ferrules 8 and 9 that are disposed at the respective ends thereof. The ferrule 9 has an opening 10 in the end thereof through which extends a screw 11 that serves as a terminal member for an external conductor. A supporting member 12 is disposed on the inner end of the screw 11 and serves to support a contact member 13, that is electrically connected thereto, and a tubular member 14 ofinsulating material.

A magnetizable member 15 of cylindrical shape is disposed within the tubular member 14 and is adapted to move therein. The

tubular member 14 has a portion 16 thereof slotted which is adapted to guide the movement of the movable member 14 by co-operating with a pin 17 that is disposed in the movable member 15. rlhe extent of the slotted portion 16 limits the extent of movement of the movable member 15.

The movable member 15 has a supporting member 18 disposed at one end thereof that supports a contact member 19 'which is electrically connected to the ferrule 9 by means of a flexible conductor 20. A restraining member 21 is disposed on the other end of the movable member 15 and is so disposed within a body 22 of material having a low melting point, such as wax, as to preclude the movement of the movable member 15 until the wax attains a predetermined temperature bearing a definite relation to the temperature of the apparatus l.

A winding 23 is connected between the ferrules 8 and 9 and is so disposed around the tubular member 14 and the movable member 15 as'to develop a magnetic field which tends to lift the member 15 thereinto. A portion 24 of the winding 23 is disposed in the body 22 of the wax and serves to heat the same in accordance with the current that traverses the winding 23. As-the current that traverses the thermal device 4 and the translating device 1 attains, or exceeds, a predetermined value, the body 22 of the wax is heated in accordance with this cur- If the current of predetermined value traverses the thermal device 4 for a predetermined interval of time, the Wax becomes sufficiently heated to permit the restraining member 21 to be'removed therefrom and, consequently, to` permit the movable member 15 to be raised by the magnetic force that is developed by the winding Q3. As the member 15'is raised, the contact members 19 and 13 are disengaged and the circuit ofthe holding magnet 5 of the interrupter 3 is consequently opened.

The interrupter 3 ris thereupon opened by the spring 6 and the translating device 1 is disconnected from thecircuit 2.

g of,a movable member responsive to the magnetic influence ofthe winding, andv means thermally influenced by the winding' for retaining, the movable member at one end of the casing and' precluding movement thereof by the windingl until heated by the winding to predetermined degree.

2f, A thermal relay comprising a cylindrical casing provided with ferr'ules at the ends thereof, a winding disposed within the casing and connected between the ferrules thereof, a movable member disposed within the winding and actuable thereby, a guide member for the movable member, and thermal restraining means normally preoluding movement of the movable member.

3f. *A* thermal relay for an electric circuit containing electric apparatus, comprising a winding connected in circuit with the apparatus, means for retain-ing the heat ofthe winding, a movable circuit-controlling member responsive to the magnetic influence of the winding and means thermal-ly influenced by the winding for restraining the movable member until the degree of heating of the winding and the thermally influenced means bears a predetermined relation to the heat4 ing of the apparatus.

4t. A thermal relay comprising a solenoid, a 'core' member actuable thereby, a contact member controlled by the core member and aV material having a low-melting poi-nt for precluding the actuation of the core member except under predetermined conditions. Y

5; A thermal relay comprising a solenoid, aV core member actuable' thereby, a contact member controlled by the core member and a material having low-melting point lfor precluding'the actna'tion of the core member` -untillgsa'id material isheated to a predetermined degree. Y

6. A thermal relay comprising a tubular member, ferrules disposed at the respective ends thereof, a winding disposed within the tubular member and connected between the ferrules, a magnetizable core member disposed in a wea-l; portion of the magnetic field ofthe winding and responsive thereto, a contact member controlled by the coremember 'winding and the compound for eecting the 'disconnection of the apparatu-si from the; circuit when the relay attains a temperature corresponding to a dangerous'temperature in the apparatus.

' 81 A circuit-protective device comprising winding, armovable member controllable y l thereby and thermally-responsive means comprising an element in circuit with the winding for precluding vactuation 'of the movable member by the winding until the thermal means attains a predeterminedcondition.

9. Afcircuit protector comprising a solenoid Winding, a movable magnetizable member subject to the influence thereof, and thermall means for precluding the actuation of the movable member except under predetermined conditions, said: Y means comprising an element in series-circuit relation with the solenoid.

10; A circuit-protective device comprising physical relation with the thermally-respon- 4 sive means and restrained thereby againstV actuation by the magnet winding and operative when said means attains a predetermined' temperature to disengage the latter under the influence ofthe winding,

V11. AVcircuit-protective device comprising a stationary operating winding, stationaryV thermally-responsive means comprising an element in series Vwith the winding, and a movable member actuable byV thewinding butV normally restrained byv the thermal means until the latter attains'a' predeter-` mined temperature. l Y, Y Y

12. A circuit-protective device comprising a stationary operating winding, stationary thermally-responsive means comprisingV an Y element in series with the Winding, and a movable member normally held by the thermal means against the pull of the Winding and released upon the development of apredetermined thermal condition in the former, and adapted to return to engage the thermal means when the Winding is deenergized.

lB. A circuit-protective device or an electric circuit containing translating apparatus comprising an electromagnetic actuating device, a member movable thereby for controlling an external circuit and thermal means having a thermal characteristic corresponding to that of the apparatus in the circuit :for precluding the actuation of the movable member until a predetermined condition is attained in the thermal means corresponding to a definite thermal condition in the appaiatus.

In testimony whereof, I have hereunto subscribed my name this 9th day of July, 1920.

THOMAS S. PERKINS. 

